Glass and glass-ceramic substrates used in consumer products may have several different intrinsic properties of interest. In certain applications, the mechanical properties of the substrate are particularly important. The optical properties of the substrate gain importance in other applications. In most applications, the substrate is configured with a combination of suitable properties that encompass mechanical, optical, thermal, and many other desirable attributes.
In certain development programs, including some display device applications, a standard set of glass and glass-ceramic materials can be employed as a starting point for a substrate. This set of materials may have an established set of mechanical properties. Accordingly, development work can emphasize the refinement of the optical properties of the substrates with the needs of the application in mind. For example, efforts may be made to enhance optical loss, optical reflectivity, transmission and color perception associated with these substrates under certain illuminations.
Coatings deposited or otherwise formed on the substrates are often optimized and configured to change and enhance the optical properties associated with the substrates. Some coatings can be quite simple using a single layer of a certain material, while some other coatings can be quite complex with hundreds of layers of a few materials. Regardless of the coating design and number of layers, it is generally expected that the substrate properties (e.g., optical transmissivity in the visible wavelengths, color perception, etc.) should not appreciably change during or after the coating deposition process. The reasoning behind this assumption is that in the design process one needs to know the substrate parameters and material parameters well in order to target the desired outcome for the particular application.
In other development programs, an application may require particular optical properties associated with a glass or glass-ceramic substrate (e.g., extremely high optical transmittance and extremely low color changes) with an extremely thick protective coating (e.g., a scratch-resistant layer) that cannot be currently obtained with known material systems and processes. That is, known approaches to providing a large increase in substrate durability through secondary coatings often result in a trade-off in loss of certain substrate optical properties.
More generally, certain glass and glass-ceramic substrates can experience optical property changes associated with secondary processing. For example, secondary processing in the form of ultraviolet light-assisted coating deposition process can break and otherwise reorganize silicate bonds in the underlying glass and glass-ceramic substrate. These bond structure changes affect the glass network and its refractive index. Further, these bond structure changes can induce the formation of defects in the glass that can affect the optical properties of the glass or glass-ceramic substrate.
In view of these considerations, there is a need for articles having, and design approaches utilizing, glass and glass-ceramic substrate-containing articles and subassemblies that are less susceptible to damage and property changes from secondary processing, including ultraviolet light-assisted coating deposition processes. Ultraviolet light-resistant articles and subassemblies can be utilized more effectively in application development programs that employ UV-assisted secondary processing, such as plasma-enhanced coating deposition. Similarly, UV light-resistant articles and subassemblies may also be optimized to obtain superior mechanical properties (e.g., through thick scratch-resistant layers) that are not otherwise obtainable with conventional substrates that are more susceptible to damage from secondary processing. It is to the provision of such technologies that the present disclosure is directed.